Foam skin cream, uses of the foam skin protection cream and a process for its preparation

ABSTRACT

A foam skin cream can be obtained by  
     preparing a phase I by melting at 75° C. a mixture containing fatty acids, especially C 12 -C 22  fatty acids, optionally unsaturated and/or polyunsaturated fatty acids, emulsifiers, coemulsifiers, such as triceteareth-4-phosphate, followed by metering it with stirring to  
     a phase II temperature-controlled at 75° C. obtained from an aqueous mixture containing moisturizers, such as propylene glycol and/or polyhydric alcohols, especially glycerol, emulsifiers, such as alkyl sarcosinates, and skin care additives, such as allantoin;  
     wherein homogeneous mixing of phases I and II is provided and said metering is performed at a temperature of 75° C.;  
     after the metered addition, the temperature is maintained at 75° C. for a period of between 5 and 20 minutes; whereupon  
     the temperature of the thus obtained mixture is lowered to a temperature of between 30 and 40° C. with constant stirring;  
     the pH value is adjusted to from 7.6 to 8.2, preferably with a skin-compatible basic organic compound, and the mixture obtained is filled into dosage forms with the addition of a propellant.

[0001] The present invention relates to a foam skin cream, uses of thefoam skin protection cream and a process for its preparation.

[0002] The galenic principle of an emulsoid two-phase system havinglipophilic or hydrophobic components and, on the other hand, hydrophiliccomponents has been known for the production of foam preparations forskin care. The application of these foam preparations to the treatedskin forms a two-dimensional two-phase network, the hydrophiliccomponents bind to the keratin of the horny layer and enable theevaporation of sweat while the lipophilic components inhibit thepermeation of moisture (including the penetrated sweat) on the skinsurface. As the foam, in contrast to other creams building a barrier, isabsorbed in less than a minute, does not leave any grease traces on theworking materials and prevents heat built-up or even maceration effectsfrom the action of sweat, the foam has enjoyed rapidly growingpopularity as a protective agent against occupational action ofmoisture. Further details about the per se known foam skin creams can beseen, in particular, from “Haut”, issue 4, 1992, by R. Rudolph, L. Bade,B. Brüggemann.

[0003] In “hautnah derm” 10 (1994), 344-351, B. Kunze reportslipid-containing skin protection foams which are indicated for drysensitive skin and chronical-rhagadiform eczemas. Ingredients are alsodisclosed therein. The skin protection foams described therein areprotective against a lot of occupational noxious matters, such as acidpermanent waving liquids in the hairdresser's trade, lyes, oils,disinfectants, cleaning and rinsing agents, but also against water,moisture, sweat, feces, urine and mineral dusts.

[0004] EP 0 598 412 also relates to skin protection foams; PTFE isdescribed as an active principle.

[0005] DE-C-33 30 628 relates to skin protection and care lotionscontaining silicone oils, partially neutralized stearic acid, fattyalcohols and their ethoxylated derivatives, ethoxylated wool alcohols,cetyl/stearyl alcohol, vaseline, thickeners and water. The lotionsdisclosed therein are said to be quickly absorbed without leaving anannoying grease film on the skin for extended periods of time.

[0006] Information about emulsifiers which can be employed in skin careagents are found in DE-A-195 42 572. This reference suggests emulsifierswhich contain from 43 to 90% by weight of alkyl and/or alkenyloligoglycosides and from 10 to 57% by weight of fatty alcohols. Theseemulsifiers are particularly suitable for the preparation of highlyviscous, sensorily light oil-in-water emulsions having a long shelflife. The German utility model DE-U-9308050 relates to a skin protectionfoam used against skin-aggressive agents. This foam consists of anaqueous emulsion containing fatty acid esters with good skincompatibility for the production of a moisture-permeable film,polyhydric alcohol for stably dispersing the active agents andcontrolling the humidity of the film, emulsifiers for improving foamstability, surfactants for reducing the surface tension and optionallyneutralizing agents for resins and emulsifiers. Gaseous hydrocarbons maybe used as propellants, for example, propane, butane or isobutane andmixtures thereof. However, the foams described do not contain any freefatty acids.

[0007] Aerosoles are complicated physical-chemical structures which donot form under arbitrary circumstances. In Particular, a special balancebetween the foam-forming components is important. Slight shifts in thecomposition may already result in a collapse of the foam; thus, aformulation of per se active substances may not be capable of beingformulated as a foam without further provisions.

[0008] Especially in occupational applications, skin creams are oftenfound unpleasant because the “fatting” components remain too long on theskin and lead to annoying finger traces or generally to an unpleasantfeeling. This has been remedied to some extent by the per se known skinfoams since they help preventing or reducing overload of the skin withthe fatting matters. Nevertheless, it is desirable to find even moreacceptance by the user, especially in the long-term use of skinprotection agents.

[0009] It has been the object of the present invention to extend theapplication range of skin protection foams by providing a formulationwhich is highly accepted by the user, the admixture of a wide variety ofother substances being allowed without destroying the aerosol employedor deteriorating the properties of the aerosol.

[0010] The object of the invention is surprisingly achieved by a baseformulation of a foam skin cream having the features of claim 1.Dependent claims 2 to 12 relate to preferred embodiments of the foamskin cream according to the invention. Claims 13 to 16 relate to uses ofthe foam skin cream according to the invention, whereas claim 17 relatesto a process for preparing the base of a foam skin cream according tothe invention. The foam skin cream according to the invention can beobtained by

[0011] preparing a phase I by melting at 75° C. a mixture containingfatty acids, especially C₁₂-C₂₂ fatty acids, optionally unsaturatedand/or polyunsaturated fatty acids, emulsifiers, coemulsifiers, such astriceteareth-4-phosphate, followed by metering it with stirring to

[0012] a phase II temperature-controlled at 75° C. obtained from anaqueous mixture containing moisturizers, such as propylene glycol and/orpolyhydric alcohols, especially glycerol, emulsifiers, such as alkylsarcosinates, and skin care additives, such as allantoin;

[0013] wherein homogeneous mixing of phases I and II is provided andsaid metering is performed at a temperature of 75° C.; after the meteredaddition, the temperature is maintained at 75° C. for a period ofbetween 5 and 20 minutes; whereupon

[0014] the temperature of the thus obtained mixture is lowered to atemperature of between 30 and 40° C. with constant stirring;

[0015] the pH value is adjusted to from 7.6 to 8.2, preferably with askin-compatible basic organic compound, and the mixture obtained isfilled into dosage forms with the addition of a propellant.

[0016] At the one hand, the product obtainable according to this processcan be directly employed as a foam skin cream in the industrial fieldfor the protection from or reduction of the absorption of cancerogenicsubstances, such as polycyclic aromatic hydrocarbons. This mixture iscapable of providing effective protection for persons whose skin hasalready been exposed to cancerogenic substances, such as polycyclicaromatic hydrocarbons. In addition, the mixture is suitable forproviding protection to persons from the action of acids, lyes (notabove pH 11), scouring agents and detergents, sweat, urine, stool,rubber gloves, dusts, house dust, machine, drilling and cooling oils,greases, paints/varnishes, gypsum and other substances and chemicals,especially aggressive substances and chemicals.

[0017] The foam skin cream according to the invention contains fattyacids, especially C₁₂-C₂₂ fatty acids, and may optionally additionallycontain unsaturated and/or polyunsaturated fatty acids. Useful fattyacids which are saturated include, in particular, the naturallyoccurring C₁₂-C₂₂ fatty acids, especially stearic acid and palmiticacid. Myristic acid may also be used. Useful unsaturated fatty acidsinclude, in particular, those having up to three unsaturated bonds intheir hydrocarbon chain. Unsaturated fatty acids are found, for example,in fractions of coconut fat. Useful coemulsifiers include per se knowncoemulsifiers, especially triceteareth-4-phosphate, sodiumlaureth-4-phosphate or oleth-3 and other lipophilic emulsifiers based onfatty alcohols with a low degree of ethoxylation.

[0018] Phase I may additionally contain paraffinum liquidum. Emulsifiersto be used in phase I may include those based on fatty alcohols andthose based on partial esters of fatty acids. Particularly preferredfatty alcohols include cetearyl alcohol. Glyceryl stearate, for example,may be employed as a partial ester of a fatty acid.

[0019] The moisturizers to be used in phase II include, in particular,propylene glycol and/or polyhydric alcohols, such as glycerol. Asparticular emulsifiers to be used in phase II, there may be mentionedalkyl sarcosinates, such as lauroyl, lauryl, cetyl sarcosinates.

[0020] The mixture obtainable according to claim 1 also serves as a basefor other foam skin creams which may be employed in a wide range ofapplications for protecting the skin and alleviating dermatologicaldysfunctions.

[0021] If desired, one or more preservatives may be added to the foamskin cream according to the invention. In particular, substances such asmethyidibromoglutaronitrile and/or phenoxyethanol have proven to besuitable preservatives. These substances may be added in amounts of from0.01 to 1% by weight.

[0022] Preferably, the emulsifiers, fatty acids, coemulsifiers,moisturizers and skin care agents, especially allantoin, panthenol etc.,are used in the following amounts:

[0023] from 4 to 15% by weight of oil-in-water emulsifier;

[0024] from 1 to 10% by weight of fatty acid, especially from 4 to 7% byweight, preferably from 4.5 to 6% by weight;

[0025] from 0.4 to 2.3% by weight of coemulsifier;

[0026] from 1 to 10% by weight of moisturizer;

[0027] from 0.05 to 1% by weight of skin care agent; and

[0028] water as the balance to make 100% by weight.

[0029] A preferable foam skin cream according to the invention contains:

[0030] from 1 to 3% by weight of glyceryl stearate;

[0031] from 3 to 6% by weight of cetearyl alcohol;

[0032] from 4 to 6% by weight of stearic acid;

[0033] from 0.5 to 2% by weight of paraffin;

[0034] from 0.4 to 2.3% by weight of triceteareth-4-phosphate;

[0035] from 1.5 to 4% by weight of propylene glycol;

[0036] from 1.3 to 4.2% by weight of glycerol;

[0037] from 1 to 3% by weight of cetyl sarcosinate;

[0038] from 0.05 to 1% by weight of allantoin; and

[0039] water as the balance to make 100% by weight.

[0040] In another preferred embodiment, the foam skin cream according tothe invention additionally contains a silicone-containing substance,such as dimethicone. This substance is added to phase I. Preferably, itis present in amounts of from 0.05 to 1% by weight.

[0041] In addition, the foam skin cream according to the invention mayadditionally contain one or more refatting substances in phase I, suchas decyl oleate, isohexadecane, stearic acid glycol ester, coconut fattyacid ethanolamide, corn oil, peanut oil, almond oil, sesame oil, oliveoil, jojoba oil, soybean oil, wool wax alcohols, paraffin, medium-chaintriglycerides, oleic acid oleyl esters, white petrolatum,macrogol-glycerol hydroxystearate, hydrogenated castor oil, castor oilfrom Ricinus communis, avocado oil, wheat germ oil, palmitic acidisopropyl ester, cetyl palmitate, myristic acid myristyl ester and/oroctyldodecanol.

[0042] In particular, the foam skin cream contains amounts of from 0.5to 2% by weight of decyl oleate and/or from 0.5 to 2% by weight ofoctyldecanol, or another of the refatting substances mentioned, if theproduct is to be used for normal skin. The total amount of refattingsubstances is to be such that the skin protection foam is not destroyed.An amount of about 4% by weight of refatting substances is sufficientfor normal to slightly dry skin. If dry skin is to be treated with thefoam skin cream according to the invention, amounts of from 3 to 6% byweight of a component of the refatting substances, such as, inparticular, decyl oleate and/or octyidecanol, are recommendable. If morethan one component is used, the total amount of refatting components isto be about 12% at most for slightly dry skin. If even more severely dryskin is treated, the amount of refatting substances is from about 6 to9% by weight if a component such as decyl oleate is used, and from 6 to9% by weight if octyidecanol is used. The amount of refatting substancemay then be up to 20% by weight.

[0043] Like the products without silicone-containing substances, thelatter foam skin creams are suitable for the care and protection of theskin, especially from aggressive substances, such as scouring agents anddetergents, sweat, urine, stool, rubber gloves, dusts, house dust,machine, drilling and cooling oils, greases, paints/varnishes, gypsumand other substances and chemicals, especially aggressive substances andchemicals.

[0044] The foam skin creams are also suitable for the treatment oralleviation of dermatological diseases. This includes, in particular,dermatological diseases such as allergic contact dermatitis type I andIV, cumulative-subtoxic eczema, toxic-irritative eczema,microbial-dysregulative eczema, atopic dermatitis, atopic palmoplantareczema, dyshidrosis, hyperhidrosis, contact urticaria, intertriginouseczema in connection with hemorrhoids, various weeping fungalinfections, e.g., interdigital mycosis, perleches, psoriasis vulgaris,ulcus cruris, cholinergic urticaria, diaper dermatitis.

[0045] It may be indicated to include substances which can increase themoisture content of the skin, in addition to refatting substances. Suchhydratizing substances include, in particular, urea, ethoxydiglycol,sodium chloride, magnesium chloride, sorbitol, dexpanthenol, sodiumlactate, allantoin, hyaluronic acid, vitamin E, linolenic acid. Theamount of those substances can be from 1 to 20% by weight or more of therespective substances, depending on the severity of the disease to betreated. These quantities also apply, in particular, to urea which mayalso be present in amounts of from 3 to 15% by weight or from 12.5 to15% by weight. The foam skin cream according to the invention may alsobe used for psoriasis.

[0046] One particularly important field of application concerns theprophylaxis and treatment of diabetic foot. Due to accompanying symptomsof diabetes, diabetics suffer from dry skin which in the course of thediseases favors damage to the extremities, up to an extent whereamputation becomes necessary in the case of those having been diabeticfor many years. Prophylactic application of skin protection agents whichprovide an improvement of the skin parameters in diabetics can preventthe development of diabetic foot.

[0047] In addition, skin care substances, such as polyunsaturated fattyacids (PUFA), may be added to the foam skin cream according to theinvention. These include, in particular, omega-6 fatty acids as known,for example, from evening primrose oil and borage oil. Both syntheticomega-6 fatty acids and those obtained from the mentioned plant extractsmay be employed.

[0048] Further, there may be used soothing substances, such as chamomileextract, as another fraction which may be admixed with the foam skincream according to the invention.

[0049] Skin-active vitamins, such as vitamins A, E and F, may be admixedwith the foam skin cream according to the invention in effectiveamounts. Especially for the treatment and prevention of diaperdermatitis, admixing the following substances has proven useful: from 3to 7% by weight of Calendula extract, from 3 to 7% by weight ofHamamelis extract, from 3 to 7% by weight of chamomile extract, from 3to 7% by weight of tea tree oil extract, from 1 to 5% by weight of decyloleate, from 1 to 5% by weight of octyldodecanol.

[0050] The process according to the invention for the preparation of thefoam skin protection cream according to the invention comprises thefollowing steps:

[0051] preparing a phase I by melting at 75° C. a mixture containingfatty acids, especially C₁₂-C₂₂ fatty acids, optionally unsaturatedand/or polyunsaturated fatty acids, coemulsifiers, such astriceteareth-4-phosphate, followed by metering this phase with stirringto

[0052] a phase II molten at 75° C. obtained from an aqueous mixturecontaining moisturizers, such as propylene glycol and/or polyhydricalcohols, especially glycerol, emulsifiers, such as alkyl sarcosinates,and skin care additives, such as allantoin;

[0053] wherein homogeneous mixing of phases I and II is provided andsaid metering is performed at a temperature of 75° C.;

[0054] after the addition of phase I to phase II, the temperature ismaintained at 75° C. for a period of between 5 and 20 minutes; whereupon

[0055] the temperature of the thus obtained mixture is lowered to atemperature of between 30 and 40° C. with constant stirring;

[0056] adjusting the pH value to from 7.6 to 8.2, preferably with askin-compatible basic organic compound, and filling into containers withthe addition of a propellant.

[0057] The invention will be further illustrated by the followingExample.

EXAMPLE

[0058] The skin protection cream according to the invention is preparedin a heatable and coolable closed apparatus with a self-withdrawinghomogenisator and a heatable metering funnel (preferably in a Korumamultipurpose apparatus).

[0059] The preparation of phase I is effected in a heatable meteringfunnel by melting at 75° C. a mixture containing 2% by weight ofglyceryl stearate, 4% by weight of cetearyl alcohol, 5% by weight ofstearic acid, 1% by weight of paraffin and 1% by weight oftriceteareth-4-phosphate, followed by metering this phase with stirringto phase II previously prepared in the heatable and coolable closedapparatus with a self-withdrawing homogenisator. Phase II consists of anaqueous mixture containing 2.5% by weight of propylene glycol, 2.5% byweight of glycerol, 2% by weight of sodium lauroylsarcosinate and 0.3%by weight of allantoin. The amount of water is 79.7% by weight.Homogeneous mixing of phases I and II is to be provided.

[0060] The metering of phase I is performed at a temperature of 75° C.Both phases are combined with constant stirring at a medium stirringspeed, and care must be taken that homogenization is effected uniformly.The temperature is maintained at 75° C. for between 5 and 20 min. Themixture obtained is cooled to a temperature of between 30 and 40° C.with constant stirring.

[0061] Then, after a temperature of 40° C. has been reached, the furthersubstances may be added. This may include adjusting the pH value tobetween 7.8 and 8.0. For this purpose, 2-amino-2-methyl-1-propanol isused. Stirring is continued for a sufficient period of time until the pHvalue has stabilized, followed by filling into suitable storage tanks orinto the corresponding spraying containers. In the latter case, 91% ofdrug is filled together with 9% of butane/propane.

1. A foam skin cream, obtainable by preparing a phase I by melting at75° C. a mixture containing fatty acids, especially C₁₀-C₂₂ fatty acids,optionally unsaturated and/or polyunsaturated fatty acids, emulsifiers,coemulsifiers, such as triceteareth-4-phosphate, followed by metering itwith stirring to a phase II temperature-controlled at 75° C. obtainedfrom an aqueous mixture containing moisturizers, such as propyleneglycol and/or polyhydric alcohols, especially glycerol, emulsifiers,such as alkyl sarcosinates, and skin care additives, such as allantoin;wherein homogeneous mixing of phases I and II is provided and saidmetering is performed at a temperature of 75° C.; after the meteredaddition, the temperature is maintained at 75° C. for a period ofbetween 5 and 20 minutes; whereupon the temperature of the thus obtainedmixture is lowered to a temperature of between 30 and 40° C. withconstant stirring; the pH value is adjusted to from 7.6 to 8.2,preferably with a skin-compatible basic organic compound, and themixture obtained is filled into dosage forms with the addition of apropellant.
 2. The foam skin cream according to claim 1, wherein apreservative is added to the mixture of phases I and II with stirring at30 to 40° C.
 3. The foam skin cream according to claim 1 or 2,containing from 4 to 15% by weight of oil-in-water emulsifier; from 1 to10% by weight of fatty acid; from 0.4 to 2.3% by weight of coemulsifier;from 1 to 10% by weight of moisturizer; from 0.05 to 1% by weight ofskin care agent; and water as the balance to make 100% by weight.
 4. Thefoam skin cream according to any of claims 1 to 3, containing from 1 to3% by weight of glyceryl stearate; from 3 to 6% by weight of cetearylalcohol; from 4 to 6% by weight of stearic acid; from 0.5 to 2% byweight of paraffin; from 0.4 to 2.3% by weight oftriceteareth-4-phosphate; from 1.5 to 4% by weight of propylene glycol;from 1.3 to 4.2% by weight of glycerol; from 1 to 3% by weight of cetylsarcosinate; from 0.05 to 1% by weight of allantoin; and water as thebalance to make 100% by weight.
 5. The foam skin cream according to anyof claims 1 to 4, additionally containing a silicone-containingcompound, such as dimethicone, in phase I, preferably in amounts of from0.05 to 1% by weight.
 6. The foam skin cream according to any of claims1 to 5, additionally containing one or more refatting substances inphase I, such as decyl oleate, isohexadecane, stearic acid glycol ester,coconut fatty acid ethanolamide, corn oil, peanut oil, almond oil,sesame oil, olive oil, jojoba oil, soybean oil, wool wax alcohols,paraffin, medium-chain triglycerides, oleic acid oleyl esters, whitepetrolatum, macrogol-glycerol hydroxystearate, hydrogenated castor oil,castor oil from Ricinus communis, avocado oil, wheat germ oil, palmiticacid isopropyl ester, cetyl palmitate, myristic acid myristyl esterand/or octyidodecanol.
 7. The foam skin cream according to claim 6,containing from 0.5 to 2% by weight of decyl oleate; and/or from 0.5 to2% by weight of octyldecanol.
 8. The foam skin cream according to claim6, containing from 3 to 6% by weight of decyl oleate; and/or from 3 to6% by weight of octyidecanol.
 9. The foam skin cream according to claim6, containing from 6 to 9% by weight of decyl oleate; and/or from 6 to9% by weight of octyldecanol.
 10. The foam skin cream according to anyof claims 1 to 9, additionally containing hydratizing (moisture-binding)agents in phase II, such as urea, ethoxydiglycol, sodium chloride,magnesium chloride, sorbitol, dexpanthenol, sodium lactate, preferablyfrom 1 to 20% by weight of urea.
 11. The foam skin cream according toany of claims 1 to 10, containing polyunsaturated fatty acids, such asω-6 fatty acids, soothing substances, such as chamomile extract, and/orskin-active vitamins.
 12. The foam skin cream according to any of claims6 to 10, containing from 3 to 7% by weight of Calendula extract; from 3to 7% by weight of Hamamelis extract; from 3 to 7% by weight ofchamomile extract; from 3 to 7% by weight of tea tree oil extract; from1 to 5% by weight of decyl oleate; from 1 to 5% by weight ofoctyldodecanol.
 13. Use of the foam skin cream according to any ofclaims 1 to 12 for the protection from or reduction of the absorption ofcancerogenic substances, such as polycyclic aromatic hydrocarbons, forpersons exposed to such substances, acids, lyes (not above pH 11),scouring agents and detergents, sweat, urine, stool, rubber gloves,dusts, house dust, machine, drilling and cooling oils, greases,paints/varnishes, gypsum and other substances and chemicals, especiallyaggressive substances and chemicals.
 14. Use of the foam skin creamaccording to any of claims 6 to 11 for the alleviation of dermatologicaldiseases, such as allergic contact dermatitis type I and IV,cumulative-subtoxic eczema, toxic-irritative eczema,microbial-dysregulative eczema, atopic dermatitis, atopic palmoplantareczema, dyshidrosis, hyperhidrosis, contact urticaria, intertriginouseczema in connection with hemorrhoids, various weeping fungalinfections, e.g., interdigital mycosis, perlèches, psoriasis vulgaris,ulcus cruris, cholinergic urticaria, diaper dermatitis.
 15. Use of thefoam skin cream according to claim 10 for the prophylaxis and therapy ofdiabetic foot.
 16. Use of the foam skin cream according to claim 12 forthe treatment and prevention of diaper dermatitis.
 17. A process for thepreparation of a foam skin cream according to at least one of claims 1to 12, comprising: preparing a phase I by melting at 75° C. a mixturecontaining fatty acids, especially C₁₂-C₂₂ fatty acids, optionallyunsaturated and/or polyunsaturated fatty acids, coemulsifiers, such astriceteareth-4-phosphate, followed by metering this phase with stirringto a phase II molten at 75° C. obtained from an aqueous mixturecontaining moisturizers, such as propylene glycol and/or polyhydricalcohols, especially glycerol, emulsifiers, such as alkyl sarcosinates,and skin care additives, such as allantoin; wherein homogeneous mixingof phases I and II is provided and said metering is performed at atemperature of 75° C.; after the addition of phase I to phase II, thetemperature is maintained at 75° C. for a period of between 5 and 20minutes; whereupon the temperature of the thus obtained mixture islowered to a temperature of between 30 and 40° C. with constantstirring; adjusting the pH value to from 7.6 to 8.2, preferably with askin-compatible basic organic compound, and filling into containers withthe addition of a propellant.